The invention relates to a drum motor for driving a conveyor belt, in particular a modular belt in hygienic surroundings involving exposure to splash water and pressurized water, said drum motor comprising a drum motor shell having a hollow space therein, motor components arranged in said hollow space, namely a rotor and a stator, a first bearing journal arranged on a first end of the drum motor shell and a second bearing journal arranged on a second end of the drum motor shell, the rotor and the stator being mechanically coupled to the drum motor shell and the first and second bearing journals in such a way that relative rotation between the rotor and the stator causes relative rotation between the drum motor shell, for the one part, and the first and second bearing journals, for the other part.
The invention also relates to a sprocket for transferring a torque from a drum motor to a modular belt.
Drum motors are known from the applicant's DE 10 2006 054 575 A1 application and EP 1 02 1664 B1 patent, for example. Drum motors of the kind initially specified are used in conveyor systems to drive conveyor belts. They have a cylindrical outer shape that is generally formed by the rod-like drum motor shell. In many cases, the drum motor shell is designed as a cylindrical hollow profile. The rotor and stator which drive the laterally arranged bearing journals rotatingly in relation to the drum motor shell are arranged as motor components in the hollow space of the drum motor shell. The drum motor is held in place at the bearing journals, while the drum motor shell drives a conveyor belt, in particular a modular belt.
Typical fields of application for conveyor systems driven by drum motors include mail distribution centres, the food processing industry, assembly lines in the electronics industry, interlinked machines in automation, production facilities, dispatch and packaging lines, warehouse picking systems, wholesale pharmaceutical distribution, pallet transport in beverage sales, cargo handling and cash desks in supermarkets, for example. In the food processing industry, in particular, where dairy produce, fish or meat, for example, is transported, drum motors must comply with the high standards of hygiene in that industry and withstand washing with chemicals and hot pressurized water. Drive systems comprising geared motors such as drum motors are a potential source of contamination in food processing. Drum motor for use in food processing must therefore be designed and treated in such a way that the risk of contamination is reduced. For that reason, such drum motors are mostly made of smooth, profiled stainless steel and are hermetically encapsulated and sealed. Modular belts made of plastic are commonly used in the food industry. To transfer the torque of the drum motor to the conveyor belt, in particular to the modular belts, profiled rubber lagging arranged on the drum motor shell can be used. The rubber profile is matched to the type of belt to be driven. Due to the profiled rubber lagging, the friction between the drum motor shell and the conveyor belt is increased and slip between the drum motor shell and the conveyor belt is prevented. However, the torque can also be transferred via sprockets, preferably of stainless steel, which have a cylindrical inner recess and are arranged on the drum motor shell. To that end, the torque is transferred from the drum motor shell to the sprockets via a feather key arranged in a groove of the drum motor shell.
These solutions already provide good torque transfer and are suitable for use in the food industry, but there is also a need for drum motors with further improved and/or simplified torque transfer and which further reduce the risk of contamination when used in the food processing industry.
As products that are manufactured in larger series, drum motors must also meet high standards in respect of both cost-efficiency and quality. The aim is therefore to reduce the production costs of drum motors without any deterioration with regard to operating characteristics, service life or maintenance intervals.
The object of the present invention is therefore to meet one or more of the aforementioned needs at least partially.